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15 Cards in this Set

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When does the arcuate nucleus of the hypothalamus begin secreting GnRH?
The second trimester.
Are any gonadotropins secreted during childhood?
Yes, small amts, but the axis in boys is more profoundly suppressed.
What is the first measurable event indicating onset of puberty?
A striking increase in gonadotropin during sleep.
What is the endocrinologic marker of adult reproductive function in women?
Positive feedback, which is the ability of the pituitary to respond to high levels of female sex hormones w/ a surge of secretory activity.
When is a reliable positive feedback mechanism established in females?
12-18 mos after menarche.
What is adrenarche, and when does it occur?
Adrenarche is the adult pattern of adrenal cortex hormone secretion; activities 17-20desmolase and 17-hydroxylase increase. This predates puberty (b/w 6 & 9 yrs).
Lesions where in the brain can trigger precocious puberty and why?
Lesions in the posterior hypothalamus; studies implicate "neuropeptide Y" and GABA pathways serve to inhibit puberty.
What is the critical weight and body composition hypothesis?
It predicts that menarche won't occur until a critical wt (48 kg or 106 lb) & sufficiently high % body fat (24%) are achieved.
What is Leptin?
A protein product of adipose tissue that may have a permissive role in the onset of puberty: gene/receptor mutations have been assoc w/ delayed puberty.
What is the role of hyperinsulinemia and insulin resistance in puberty?
Both of these are assoc w/ obesity and somehow mediate the onset of puberty.
What is the first sign of pubertal development in girls?
Breast Budding
When does menarche occur?
About two years after onset of puberty.
What is the first sign of pubertal development in boys?
Enlargement of the gonads.
What are the two effects of gonadal steroids on pubertal growth?
1) Induce inc in GH secretion, which stimulates IGF-I from liver.
2) Stimulate local production of IGF-I and other growth factors in cartilage and bone.
Which type of gonadal steroids is necessary for normal skeletal growth and maturation in both girls and boys?
Estrogen